The invention disclosed herein pertains generally to AC power relays and specifically to a solid state implementation thereof. The invention was made under or in the course of a contract with the Department of the united States Air Force.
The development and ready availability of various solid state electronic devices has stimulated an interest in a viable solid state replacement for the old reliable electromagnetic relay for controlling the flow of AC power while affording electrical isolation between the switching path and the actuating control elements. The distinct advantages in faster operating time, smaller and cheaper fabrication and greater reliability to be achieved with a solid state design are all well recognized. Although a number of solid state AC power relays have been developed, they exhibit a certain degree of unnecessary complexity which engenders a level of sophistication uncalled for in many applications and consequently economically militates against their usage. These relays, which normally employ some type of trigger device such as an SCR or a triac, are quite often copiously designed to ensure triggering the device into conduction as close to the AC zero crossings as possible in order to avoid undesirable signal interference effects resulting from high inrush currents and ringing. In addition to increasing fabrication cost and size, these overdesigns also result in higher power dissipation losses during the off-state of the relay.
With the foregoing in mind, it is a primary object of the present invention to provide a new and improved solid state AC power relay which employs a trigger type device whose control is effectuated through a simple circuit design.
It is a further object of the present invention to provide such a new and improved solid state AC power relay which ensures conduction essentially at the AC zero crossings and which minimizes power dissipation during the off-state of the relay.
The foregoing objects as well as others and the means by which they are achieved by the present invention may best be appreciated by referring to the Detailed Description of the Invention which follows hereinafter, together with the drawings.